Turbomachinery blade retainer

ABSTRACT

Means for retaining a blade in a turbomachinery rotor includes a locking clip and a spacer. The clip includes preformed legs at each end which are adapted to abut the opposite sides and ends of the disc and blade root. One leg includes a preformed tab for retaining the spacer and is sized to permit insertion of the clip under the blade. The other leg includes a tab which is formable from a position enabling insertion of the spacer under the blade to a position abutting and locking the spacer.

D United States Patent 1151 3,653,78 1

C00 er [4 1 A r. 4 1972 54] TURBOMACHINERY BLADE 3,353,788 11/1967 Weeds ..4l6/221 RETAINER 3,383,095 5/1968 Anderson .....416/220 3,395,891 8/1968 Burge et a] ..416/220 [72] Inventor: James Lee Cooper, Cincinnati, OhlO 73 A G El C Primary Examiner-Everette A. Powell, Jr. 1 sslgnee 2 cc r c ompany Attorney-Derek P. Lawrence, Erwin F. Berrier, Jr., Lee H. Flled! 1970 Sachs, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. 211 App]. No.: 99,391 Fmma [57] ABSTRACT (g1 Means for retaining a blade in a turbomachinery rotor in cludes a locking clip and a spacer. The clip includes [58] Field of Search ..4i6/22l, 220 preformed g at each end which are adapted to abm the p [56] References Cited posite sides and ends of the disc and blade root. One leg includes a preformed tab for retaining the spacer and is sized to UNITED STATES PATENTS permit insertion of the clip under the blade. The other leg includes a tab which is formable from a position enabling inser- 13; g r z-"l tion of the spacer under the blade to a position abutting and a i y e e a lockin thes acer. 3,076,634 2/1963 Boyle et al...... ..416/221 g p 3,216,699 1 1/1965 Schoenborn ..4l6/220 X 4 Claims, 4 Drawing Figures PATENTEDAPR 4 I972 3,653,781

INVENTOR. JAMES L. COOPER ATTORNEY- TURBOMACHINERY BLADE RETAINER This invention relates to turbomachines and, more particularly, to improved means for retaining blades in turbomachinery rotors. The invention herein described was made in the course of or under a contract, or a subcontract thereunder, with the United States Department of the Air Force.

Blade locks which have been heretofore proposed for use in axially locking a blade within a generally axial rotor or disc slot usually include one or more tabs which are bent to lock the blade within the disc slot. Such arrangements are, however, undesirable in that the axial forces required to axially retain the blade are transmitted through or reacted by a member which has been bent during assembly. In addition, the bent tab usually has residual strain which may result in springback or slight movement of the tab toward its unbent position and undesirable axial looseness of the blade.

In some applications, only one side of the turbomachinery disc is accessible in the assembled turbomachine. In such cases, it is highly desirable, from a field maintenance standpoint, that the blade retaining means be adapted for installation and removal from the accessible side of the disc so as to eliminate the necessity for extensive disassembly of the turbomachine in replacing a blade.

A primary object of this invention, therefore, is a blade retainer or lock that may be installed and removed from one side of the disc, overcomes the foregoing disadvantages, and is relatively simple and economical in construction and installation.

Briefly stated, the above and other objects and advantages of the present invention, which will become apparent upon reading the following description of the preferred embodiment, are achieved in the present invention by providing a cooperating locking clip and spacer. The locking clip includes preformed legs at each end which extend generally at right angles from the ends of the strip. The legs are sized to abut both the blade root portion and the disc to prevent relative axial movement therebetween. A first one of the legs is sized to enable insertion of the clip under the blade root. The spacer is sized for insertion under the blade root to maintain the locking clip in its locking position. The first leg includes a depending tab portion which abuts the inserted end of the spacer to axially retain the spacer in one direction. The second leg includes a tab which is bent radially inwardly to axially retain the spacer in the other direction.

It is believed that the present invention will be better understood upon reading the following description of the preferred embodiment taken in connection with the accompanying drawing wherein:

FIG. 1 is a partially exploded perspective view showing a portion of an exemplary rotor blade assembly having one blade removed and employing the blade retaining means of this invention;

FIG. 2 is an enlarged elevational view, in partial cross section, showing the blade retaining means of FIG. 1;

FIG. 3 is a view taken along lines 3-3 ofFIG. 2; and

FIG. 4 is a view taken along lines 44 of FIG. 2.

Referring now to the drawing and particularly to FIG. 1, a portion of a rotatable turbomachinery rotor or disc has been shown at 10. The disc is formed with a plurality of slots 12 at its periphery which extend from one side 14 of the disc to the other side 16. Suitable turbomachinery blades, as for example fan, compressor or turbine blades, have been shown at 18 as comprising an airfoil portion 20, a platform portion 22 and a root portion 24.

Each blade root 24 is formed with oppositely facing end surfaces 26 and 28, a bottom surface 30 and oppositely facing sidewalls 32 which are suitably shaped in cooperation with the sidewalls of its slot 12 so as to radially lock the blade to the disc 10.

The blade root 24 and the slot 12 are suitably size so that when the root sidewalls 32 are in radial locking abutment with the sidewalls of slot 12, a passage 34 is defined under the blade root bottom surface 30.

The blade retaining means of this invention have been shown generally at 36 in FIG. 1 as comprising a metallic locking clip 38 and a cooperating spacer 40. The locking clip 38 includes an elongated bridge member or strip portion 42 having a first leg 44 at one end and a second leg 46 at its other end. The legs 44, 46 extend radially outwardly from the strip 42 generally parallel in the plane of their respective disc sides 14 and 16. a

As best shown in FIG. 4, the leg 46 is sized with a radial height X slightly less than the radial height of the passage 34 to facilitate insertion of the clip 38 under the blade 18 to the position of FIG. 2. The leg 46 includes a tangentially extending tab portion 48 adapted to abut disc side 16, and a radially inwardly extending tab portion 50 adapted to abut one end of the spacer 40.

The leg 44 extends radially outwardly from the strip portion 42, as viewed in FIG. 3, and is sized to abut the disc side 14 and the end surface 26 of blade root 24. The leg 44 includes a radially inwardly extending tab 52 to permit the spacer 40 to be locked in the position of FIG. 2 beneath the blade root 24. The tab 52 is initially disposed in the position of FIG. I, wherein it extends away from the strip portion 42 or is bent sufficiently out of the plane of the main portion of leg 44 so as to not extend below the root bottom surface 30 as is generally shown and with the clip positioned as in FIG. 2. The tab 52 is sufficiently long'so that, when it is bent into the plane of the leg 44, it will extend below the bottom surface 30 of the blade root and abut and axially lock the spacer 40.

The spacer 40 may be formed of any suitable material, metallic or otherwise, and is sized, in cooperation with the locking clip 38, to take up the radial height of the passage 34. To prevent circumferential movement of the key 38 relative to the disc 10, and hence wear and chafing associated therewith, the spacer 40 may be formed with a recess or slot 54 along one upper longitudinal edge thereof which is sized in width and radial height to receive the strip portion 42 of the clip 38.

The use, operation and function of the present invention are as follows:

In assembly of a bladed turbomachinery rotor using the retaining means of this invention, the locking clip 38 is inserted, leg 46 end first, under the blade root 24 until leg 44 abuts the root end surface 26. The locking clip 38 is then moved radially outwardly to the position of FIGS. 3 and 4 wherein the legs 44, 46 tightly grip the opposite sides and ends of both the disc and the blade root and thereby lock the blade against axial movement within the slot 12.

In order to hold the blade 18 in its spaced position relative to the bottom of slot 12 and maintain the clip 38 in its locking position, the spacer 40 is inserted into the leg 44 end of passage 34, with the strip 42 engaged in slot 54, until the inserted end of the spacer abuts the depending tab 50 of leg 46 and prevents further movement in that axial direction. Tab 52 of leg 44 is then bent radially inwardly into the plane of leg 44 wherein it abuts the other end of spacer 40 and axially locks the spacer within the slot 12.

As will be apparent, the blade 18 may be readily removed from its locked position by simply reversing the above procedure.

Since the leg 46 and the portion of leg 44 which operates to axially lock the blade within the slot 12 are not bent at assembly, the spacing between legs 44 and 46 can be accurately established and it will be appreciated that the present invention avoids problems associated with axial looseness of the blade due to tab springback. The locking clip 38 is subject to economical fabricating methods, such as stamping, which do not require machining. In addition, by preforming the legs 44 and 46, the bends between legs 44 and 46 and the strip 42, where necessary, may be appropriately heat treated and in all cases thoroughly inspected.

From the foregoing, it will be appreciated that the present invention provides means, for retaining a blade axially tight within its disc slot, which may be installed and removed with access to only one side of the disc and which is of simple and economical construction and installation. While a preferred embodiment has been depicted and'described, it will be understood that such is intended to be exemplary only and not definitive and that numerous modifications, additions and changes may be made thereto without departing from the fundamental theme of the invention.

What is claimed is:

1. Means for axially retaining a turbomachinery blade in a disc of the type having first and second side surfaces and a root-receiving slot extending transversely of said disc at its locking position wherein the disc and blade root are received between said legs, with said legs abutting opposite sides and ends of said disc and said blade root, and a spacer sized for insertion in said passage to maintain said clip in said locking position.

2. The structure of claim 1 further characterized by and inv cluding means for retaining said spacer in said passage.

3. The structure of claim 2 further characterized in that said spacer retaining means comprise a first radially inwardly extending tab carried by one of said legs for abutting the inserted end of said spacer, a second tab carried by the other leg of said clip, said second tab disposed in a position enabling insertion of said spacer and deformable to a position abutting the other end of said spacer.

4. The structure of claim 1 further characterized in that said spacer is formed with a slot for receiving said strip whereby relative circumferential movement between said disc and said clip is constrained. 

1. Means for axially retaining a turbomachinery blade in a disc of the type having first and second side surfaces and a rootreceiving slot extending transversely of said disc at its periphery, said blade having a root portion engaged in said slot, said slot and said root portion being shaped to abut and radially lock the blade to the disc against centrifugal forces and define a passage beneath said blade root, said retaining means comprising: a locking clip comprising a strip portion and first and second preformed legs extending generally radially from the ends of said strip, said second leg having a radial height less than that of said passage to enable insertion of said clip, said strip sized such that said clip is movable to a locking position wherein the disc and blade root are received between said legs, with said legs abutting opposite sides and ends of said disc and said blade root, and a spacer sized for insertion in said passage to maintain said clip in said locking position.
 2. The structure of claim 1 further characterized by and including means for retaining said spacer in said passage.
 3. The structure of claim 2 further characterized in that said spacer retaining means comprise a first radially inwardly extending tab carried by one of said legs for abutting the inserted end of said spacer, a second tab carried by the other leg of said clip, said second tab disposed in a position enabling insertion of said spacer and deformable to a position abutting the other end of said spacer.
 4. The structure of claim 1 further characterized in that said spacer is formed with a slot for receiving said strip whereby relative circumferential movement between said disc and said clip is constrained. 